See bottom for cliff notes.
For wired routers, all consumer products are about the same. I don't have any experience with their wireless B products so you'll have to ask someone else about them.
However, I have found some good point and bad points about their wireless G products. First I had a D-Link DI-624 Super G wireless router. Worked great, rebooted randomly every 2 or 3 days, but not a big deal. It's counterpart laptop card the DWL-G650 Super G PC card was a problem till dslreports pointed me to the atheros drivers which made the card 100% stable instead of losing link like 6-8 times a day with the d-link software.
So after much work I was satisfied with D-Link, until I wanted to wirelessly connect my Xbox to my network. I plan to connect an Xbox and possibly a few more tv using devices (PS2 or ReplayTV) and none of the D-Link Super G products would work with more than 1 device and they were every expensive, almost twice the cost of the router.
After researching and being disappointed by the D-Link DWL-2100AP and the DWL-G810 I decided to give my DI-624 to my sister who only wants to connect her wireless B laptop to her cable modem, and buy a pair of WBR2-G54 Buffalo Tech routers. I thought all consumer grade routers were aboiut the same. Well that's not quite the case with wireless G products. It seems that routers based off the Broadcom chipset have more features. The feature I got the Buffalo routers for was their ability to do bridging/wireless access all at the same time. D-Link devices if they are capable of doing multiple things, can't function in multiple modes at the same time. They also don't interoperate with each other very well.
If I had stuck with D-Link, I would have had to buy 2 DWL-2100AP + a 4 port switch and I would still need my DI-624. By switching to Buffalo, I only had to buy 2 of their routers to accomplish the same thing.
Also if you're into installing modified firmware to get some cool new features, go with the Linksys WRT54G/GS. It has open source firmware (based off linux) so people are adding new features. Buffalo WBR-54G and Belkin F5D7230-4 use the same chipset (hence also open source), and firmware changes made to the Linksys are planned to be ported to these 2 routers too.
So finally a conclusion, why buy a D-Link when for the same money you can get more functionality out of one of the following: Linksys WRT54G or GS, Buffalo Tech WBR-54G or Belkin F5D7230-4. Even if you don't need bridging or the new features now, later down the road you might want them.
CLIFF NOTES: D-link ok if all you want is a wireless router, bad if you want WDS bridging. Buy Linksys WRT54G, Buffalo Tech WBR-54G or Belkin F5D7230-4.
PS: I never had to call Buffalo Tech tech support so I can't comment on how good or bad they are.